/*
GanttProject is an opensource project management tool.
Copyright (C) 2003-2011 GanttProject Team

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 3
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/
package net.sourceforge.ganttproject.filter;

import java.io.File;
import java.util.regex.Pattern;

import javax.swing.filechooser.FileFilter;

/**
 * Class to select a filter for the FileChooser object for the provided extension
 *
 * @author bard
 */
public class ExtensionBasedFileFilter extends FileFilter {
    private final String myDescription;

    private final Pattern myPattern;

    public ExtensionBasedFileFilter(String fileExtension, String description) {
        myDescription = description;
        myPattern = Pattern.compile(fileExtension);
    }

    @Override
    public boolean accept(File f) {
        if (f.isDirectory()) {
            return true;
        }
        return matches(getExtension(f));
    }

    @Override
    public String getDescription() {
        return myDescription;
    }

    /** @return extension of File f */
    private static String getExtension(File f) {
        String ext = null;
        String s = f.getName();
        int i = s.lastIndexOf('.');

        if (i > 0 && i < s.length() - 1) {
            ext = s.substring(i + 1).toLowerCase();
        }
        return ext;
    }

    private boolean matches(String fileExtension) {
        boolean result = fileExtension != null
                && myPattern.matcher(fileExtension).matches();
        return result;
    }
}
